ARCHIVED REPORTS XR0011068 - Laserfiche WebLink

Home Browse Search

' eCo&gceal rechnxs Ific Page 2 Groundwater Monnormg Report Project No 724 2 August 11,2003 1.0 GROUNDWATER MONITORING 1.1 Hydrogeology of Site ' Site-specific groundwater gradients and bearings for water table and intermediate wells were calculated utilizing computer generated contours ' On June 30, 2003, the gradient in water table wells MW-4, MW-5, MW-6 and MW-7 was flowing S45°E at 0 0071 ft/ft Figure 2 illustrates the water table groundwater gradient map for the monitoring event The average elevation of groundwater under the site was —21 43 feet MSL (below mean sea level) and this represents a decrease of -0 77 feet since the March 13, 2003 monitoring event The water level has risen significantly at the site since ' October of 1992 when groundwater was—39 feet MSL Figure 3 is an intermediate well groundwater gradient map for the June 2003 event In the intermediate wells (water above the screened interval of the well) MW-1 through MW-3, MW-106 and MW-107, groundwater flowed S86°E at a gradient of 0 0014 ft/ft Deep well MW-104 is not screened across similar elevations so a deeper gradient was not calculated for the event (see Table 6 for well construction details) Table 1 in Appendix A contains the shallow groundwater elevations and gradients for all ' events since the start of this project in October 1992 Table 2 in Appendix A contains the historical intermediate/deep groundwater elevations The rose diagram included in Figure 4A shows that the water table groundwater gradients at this site are consistently towards the east In Figure 4A, arrows labeled 22 and higher were ' measurements made after November 2000 Since additional wells were installed in November 2000, the groundwater direction has had a more southerly component suggesting that the earlier measurements were biased due to the spatial orientation of fewer wells The ' rose diagram included in Figure 4B shows that the intermediate aquifer gradients at this site range from northeast to southeast The gradients were consistently to the east for the last five events Vertical Groundwater Gradients Under vertical groundwater flow conditions, the water level in a monitoring well is a 1 function of the length of the well screen and its depth or vertical position in the aquifer As with horizontal flow conditions, the diameter of the well or piezometer is immaterial ' The following procedure is used to calculate the vertical groundwater gradient • Determine vertical distance between the two measuring devices by the distance from the mid-point between the top and bottom seal of the deep well (MW-104, MW-106, MW-